Multicore power cable



Jan. 29, 1935. w, VOGEL Er AL 1,989,346

MULTICORE POWER CABLE Filed Sept. 8, 1952 9L mqrmaon INVCNTORJ Patented Jan. 29, 1935 I I UNITED STATES PATENT OFFICE MULTKCOBE POWER, CABLE Wilhelm Vogel and Karl Baurmann, Cologne- Mulheim, Germany, assignors to Felten & Guilleaume Carlswerk Actien-Gesellschaft, Cologne-Mulheim, Germany Application September 8, 1932, Serial No. 632,224 In Germany July 10, 1931 1 Claim. (01. 173-266) In the operation of power cables, more particurate cable cores provided with an impervious larly high tension cable's, it is of great importance sheath and the protective wires are led out, firmly to be able to detect in the early stages external embraces both the sheaths of the separate cores damages which sooner or later must cause leakand also the protective wires and thereby provides 5 ages or short-circuits and to ascertain where the a moisture-tight closure. The cable cores and 5 fault has occurred. In the present state of the auxiliary wires which are led out of .the outer art and the practical experiences with cables, it cable sheath in this manner terminate in sepawould appear to be the most suitable plan to rate end closures. These auxiliary wires may be mount the protective devices outside the cable inplaced in the cable by introducing one or more sulation, as it has been found that almost all faults ordinary telephone conductors when laying the 10 occurring in the cables and sleeves may be traced cores of the multi-core cable.

to external influences (mechanical damage or When the cable is in operation and undamaged, corrosion). the normal cable temperature is ascertained by a Cable arrangements are known in which conresistance test. Should the cable, however, be

ductors having an insulation which is sensitive damaged from the outside, the moisture penetrat- 15 to moisture are disposed in the insulation of the ing through the faulty place of the outer sheath cores or in the gusset-shaped parts of the insulawill in a short time be absorbed by the dry paper tion. These arrangements, however, all have the insulation of the signal wires and their insulation disadvantage that the testing wire and the cable value reduced. This deterioration of the insulaconductor insulation are housed in one and the tion value is then utilized for putting a warning 20 same mechanically strong and closely-fitting signalling device into operation, whereupon the sheath so that although any damage to this position of the damage can be ascertained in a sheath will cause the testing wires to respond, known manner by the loop method of fault localiit will also have thedisadvantage of causing the ration. As the impregnated cable insulation re- 5 cable insulation proper to deteriorate. The presacts very slowly to moisture, the signal system ent invention is based on the fact that when such which is connected to the telephone cores will, auxiliary conductors which are insulated with dry, even in the case of serious damage (for instance unimpregnated highly hygroscopic paper are in the case of submerged cables), always respond housed in multi-core cables, outside the conduc-v sooner than a cable fault can develop in the main tor insulation and completely separated thereinstallation. The arrangemen made use Of n 30 from, the moisture penetrating through the damthe method described above has the further adaged place of the outer common cable sheath into vantage that with it it is always possible to deterthe dry paper insulation of these c nductors can mine the mean temperature of a cable at any be utilized for determining theposition of thefault time so that steps may be taken as regards the Without there being any dang of e o du maximum admissible current load. This provides 35 insulation being detrimentally affected. For this the ossibility, for instance in the winter ,when

purpose, 1n multi-core cables mwhich three insuthe 11 is very cold, of loading the cable more lated cable cores surrounded with an impervious heavily than in the Summer without exceeding metafl Sheath are enclosed P outer imthe admissible maximum temperature, which is pervmus metal sheath p finm-g the of special value in view of the fact that the cursetfshaped spaces cnductmg.wues having a rent consumption is usually higher in the winter. unimpregnategltgaper insulation are disposed in The accompanying drawing shows the cable one or more 0 e said gusset-shaped spaces and are connected outside the cable (at the cable ends arrangement used a are the lmpervmus sheaths or at the junction sleeves) toarelay system which over the core insulation b the outside covering 45 indicates faults in the insulation of the telephone the wh1e cable (lead Sheath) a 0 nd t d t t Same t enables the tective conductors (telephonescores) which are cable temperature to be ascertained by checking insulated with dry unimpregnatefi P In the resistance. At the ends of the cable, the cable the measuring device for 8566351111118 me ab e cores and the protective wires mustbe led out of fault cable temperature, which is illustrated 50 the outer sheath in such a manner that neither n t drawi d s n t d t h pr t t v air nor moisture can penetrate into the gusset-i conductors 6 and the Outer lead Sheath b, 3, shaped spaces of the cable. For this pu pose, a n. and r2, fa, 4 are bridge resistances, R relays closing cap is placed on the ends 0! the external and T a temperature indicating instrument (zero v cable sheath, which, at the places where the sepainstrument). 5

What we claim is:-

tion and grouped in said space between the cores,

A power cable comprising a plurality of cores and dry unimpregnated paper of relatively high moisture absorptive quality coverin'g said conducsaid external sheath.

tors and directly exposed to moisture penetrating I 

